Prior art planning operations generally provide point-to-point routing through a deterministic set of points. The prior art plans assume that the desired resource is available at each point. Furthermore, the prior art planning operations assume that a user can follow the plan. The plans generally do not account for a user missing a turn-off, traffic jams, closed roads, detours, or the user failing to follow a plan. These services do not provide contingency planning for handling such failures in the route.
GPS mapping devices use similar techniques. These services provide a solution for handing failures that arise when the user executes the route. For example, they may detect the failure in real-time and recomputed the route reactively—i.e. in reaction to the failure. The problem with this type of reactive recalculation is that it is time consuming. This can cause delays as the user waits for the new route, which is a major inconvenience if the user is moving at a high velocity along a busy highway. The delays can also cause other types of plan failure due to the time required for recomputation causing the user to miss a turn that would have quickly corrected for the previous failure.